Vibronic studies of adsorbate-covered semiconductor surfaces with the help of HPC

The technologically relevant adsorbate systems S:Ge(001)-(1 x 1) and Se:Ge(001)-(1 x 1) are prototypes for the passivation of semiconductor surfaces. Over the last years, their electronic and structural properties have been studied by ab-initio methods in detail, while the description of vibronic properties was limited to semi-empirical methods. The use of high performance computing (HPC) allows for the first time the calculation of surface phonons for these particular systems from first principles within a reasonable time, for example with the help of density functional perturbation theory. This theory, its implementation on a parallel computer and results concerning the vibronic properties of the above-mentioned surfaces are presented in this article.